Assessment of amber-PBAT interactions in melt-mixed composites: A comparative study between extruded films and injection molded specimens

This study investigates the interaction between poly(butylene adipate-co-terephthalate) (PBAT) and amber powdered waste (AbW) from jewelry at different filler concentrations (0, 1, 2.5, and 5 wt%) obtained via melt mixing in a corotating twin screw extruder. The resulting materials were pelletized and processed using two techniques: 1) cast film extrusion and 2) injection molding. The shaped specimens exhibited excellent interfacial adhesion. Thermal behavior, as assessed by Vicat softening temperature (VST), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA), showed minimal variation among the composites. Despite similar melt flow rate (MFR) values among the samples, the incorporation of AbW affected the behavior of the polymer during cast film extrusion. Consequently, the composite films exhibited lower tensile mechanical parameters (tensile strength, Young’s modulus, stress and strain at break) compared to the neat PBAT film. In turn, the injection molded composites showed improved tensile, flexural, and impact parameters compared to their neat counterpart. Additionally, a slight decrease in water contact angle (WCA) suggested increased surface hydrophilicity of the extruded films. These findings demonstrate the potential of AbW as an additive for biopolymer composites with enhanced mechanical performance. The increased surface hydrophilicity is particularly relevant for applications targeting biocompatibility and biodegradability.